The present invention relates to a novel disc centering mechanism in a disc playback and/or recording apparatus. More specifically, the invention relates to a technique for increasing the positioning accuracy of centering of a disc shaped recording medium and enabling its use in what is called a vertical installation state.
In conventional disc playback and/or recording apparatuses, a disc is centered by means of two centering shafts.
FIGS. 1-4 outline such a conventional centering mechanism.
The centering mechanism has two swing arms 1 and 2 that swing in opposite directions in synchronism with each other, and centering shafts 3 and 4 are supported by the swing arms 1 and 2 at their tip portions. A resilient means (not shown), which is provided between the swing arms 1 and 2, provides turning force that urges the tip portions of the swing arms 1 and 2 in such directions as to cause the swing arms 1 and 2 to come closer to each other. And a stopper means (not shown) causes the swing arms 1 and 2 to stand by at the positions shown in FIG. 1.
A disc 100 is pulled into the apparatus by a pull-in roller 5 (see FIG. 2).
When the disc 100 is pulled into the apparatus, first the outer periphery of the recording medium 100 butts against the two centering shafts 3 and 4 that are in the stand-by state (see FIGS. 1 and 2) as shown in FIG. 3. When the disc 100 is further pulled in, its outer periphery pushes the two centering shafts 3 and 4, to turn the swing arms 1 and 2 against the turning force provided by the resilient means, whereby the disc 100 is pulled in to a predetermined pull-in completion position (see FIG. 4). At this time, the disc 100 is centered in such a manner that its outer periphery is pressed against the centering shafts 3 and 4 at two locations. When the disc 100 has been pulled in to the pull-in completion position (see FIG. 4), the pull-in completion is detected by a sensor .(not shown), whereupon the rotation of the pull-in roller 5 is stopped and the pull-in roller 5 goes away from the disc 100. The disc 100 is then chucked by a chucking means (not shown).
By the way, in the conventional disc playback and/or recording apparatus, the disc 100 is centered in such a manner that its outer periphery butts the centering shafts 3 and 4 after it is pulled into the apparatus by the pull-in roller 5. Therefore, there may occur a case that the disc 100 is not in a proper positional relationship with the pull-in roller 5 at a time point when it starts to be pulled in by the pull-in roller 5. In particular, when the disc 100 is used in a vertical installation state, that is, when it is used in a state that its recording surface is parallel with the vertical direction, the positioning accuracy of the centering tends to be low and even erroneous chucking may occur.
A central portion of the pull-in roller 5 is constricted so as to prevent its outer circumferential surface from contacting the recording surface of the disc 100 and damaging the recording surface (see FIGS. 1-4). Therefore, if the center line of the disc 100 does not coincide with the center of the pull-in roller 5, the torque of the pull-in roller 5 does not equally act on the right and left portions of the disc 100, possibly causing a problem that the disc 100 is pulled in while being rotated.
The disc 100 that is pulled in while being rotated not only appears bad but also is rendered unstable inside the apparatus, possibly causing erroneous chucking.
An object of the present invention is therefore to increase the positioning accuracy of centering of a disc and to enable its use in what is called a vertical installation state.
Another object of the invention is to have a disc positioned correctly with respect to a pull-in roller at a time point when the pull-in roller starts to pull in the disc.
To attain the above objects, the invention provides a disc playback and/or recording apparatus having means for centering a disc, comprising a pair of centering members having a plurality of shafts and capable of moving in synchronism with each other in opposite directions that are perpendicular to the pull-in direction of a disc and parallel with the recording surface of the disc; and a driving mechanism for centering the disc by causing the outer periphery of the disc to butt the shafts.
In the above disc playback and/or recording apparatus of the invention, since the disc is centered by causing its outer periphery to butt the shafts (two pairs of, i.e., four, centering shafts), the centering can be effected with high accuracy. Further, even where the disc is used in a vertical installation state, it can be centered in a reliable manner.
Further, the invention provides a disc playback and/or recording apparatus comprising two positioning members that are separated from each other in a direction that is perpendicular to the pull-in direction of a disc and parallel with the recording surface of the disc and that are capable of moving in synchronism with each other in opposite directions in the above direction, wherein the disc is positioned in such a manner its outer periphery butts the positioning members.
In the above disc playback and/or recording apparatus of the invention, the disc can be positioned precisely.